A convicted killer could go free 27 years after admitting to murder, thanks to a Georgia Supreme Court ruling Monday.

Fulton County District Attorney Paul Howard Jr. plans to challenge the decision, or at least make sure that Curtis Tyner remains in a state prison for killing Martha Anne Mickel in April 1984.

“There is no debate with respect to who suffers most from this decision – the family members of Martha Anne Mickel who thought that this matter was concluded 27 years ago with a guilty plea,” Howard told The Atlanta Journal-Constitution Monday.

Mickel’s brother Joe Mickel, himself an attorney, struggled to pay respect to the prosecution and judge that heard Tyner’s plea years ago, and to the state Supreme Court. Still, Joe Mickel’s response was curt: “It’s appalling.”

The opinion, written by Justice David Nahmias, pointed out that no one fully informed Tyner, then 36, of all the rights he was waiving when he made his guilty plea.

"The record does not show that Tyner was advised of his right against self-incrimination," Nahmias wrote in the opinion he filed Monday morning. "His guilty plea was invalid and we must reverse his conviction."

But Harvey Moskowitz, the Fulton County assistant district attorney prosecuting the case at the time, argued that he, Judge Isaac Jenrette and public defender Carl Greenberg did everything according to the letter of the law.

“Greenberg, myself and the judge advised him of his rights as we knew them at the time,” Moskowitz told The Atlanta Journal-Constitution. “I don’t see why this was overturned.”

Martha Mickel was a 30-year-old executive for IBM in 1984. On the weekend of April 15, the Smyrna woman didn’t show for a wedding she was to attend with her boyfriend.

She also didn't attend church the next day. Her body was found later that Sunday, floating in Bear Creek in south Fulton County.

Fulton County police determined that Mickel had hired Tyner to paint her townhouse, and investigators went to his Forest Park home. During their stakeout, he left, went to a pay phone to call police, saying, “I think you’re looking for me,” according to court documents.

After Tyner was arrested and charged with Mickel’s death, he confessed that he had bound Mickel with duct tape and put her in her car.

A medical examiner pointed to ligature markings indicating that she had been tied around the neck to her automobile’s headrest. Her hands were tied, the buttons to her blouse had been ripped off and her pants were open.

Tyner told police that when she slumped over in the car, he thought she was dead and panicked. He said he threw her in the river, not knowing she was still breathing.

The medical examiner ruled Mickel’s cause of death drowning.

“I found it to be unconscionable that he would do that,” said Moskowitz, who is now retired and is on the board of the Atlanta Law School Foundation.

But Charles Frier, who appealed the case on Tyner’s behalf, said he was pleased with the outcome.

“I’m delighted that he finally got it overturned and the obvious error was seen,” Frier said.

The state Supreme Court indicated that authorities failed to tell Tyner everything he needed to know before agreeing to a guilty plea, citing precedence set by the 1969 ruling of Boykins v. Alabama.

That ruling states suspects wishing to plead guilty must be informed of three things: They are waiving the right to a jury trial, the right to confront their accusers and the right to choose not to testify in a trial.

Frier argued that his guilty plea didn't pass "constitutional scrutiny" because he wasn't advised that he didn’t have to take the stand.

In the transcript of the hearing, neither the judge, the prosecutor nor the public defender explicitly explain to Tyner his right not to self-incriminate, which Frier’s filing highlights.

Frier said the administrative process to release Tyner, now 63, from the Wilcox State Prison in downstate Abbeville could take weeks. Even then, Tyner might only land back in Fulton County jail, since he never posted bail -- and he may find the same indictment waiting for him that his defense waived the reading of in 1984.

The next move belongs to Howard. Frier will ask whether the district attorney wants to negotiate a new plea deal, or go to trial -- something that has never happened.

Howard plans to take the case back to the state Supreme Court.

"We feel very strongly that this case must be reconsidered," he said.